Crystal Engineering of a Permanently Porous Network Sustained Exclusively by Charge-Assisted Hydrogen Bonds

摘要

In the synthesis of network solids from molecular components, that is, crystal engineering, two omnipresent challenges are the ability to accurately design an infinite assembly based on the structures of molecular building blocks and the ability to generate permanent pores in the material. For solids based upon weaker interactions (i.e., excluding covalent bonding or strong M-O bonding), the difficulties raised by these two issues are both alleviated and aggravated. Using noncovalent interactions allows reversibility during assembly, giving access to the thermodynamic product. This supramolecular "error-checking" facilitates formation of designed products. However, formation of a porous solid requires that the network sustaining interactions are of sufficient strength to pay the energetic penalty for existence of the pores themselves. In this sense, weak interactions are clearly unfavorable.